bb6563f363
This commit moves the TH structs and definitions to model. We don't want oohelperd to depend on web_connectivity@v0.4. Part of https://github.com/ooni/probe/issues/2240
107 lines
3.3 KiB
Go
107 lines
3.3 KiB
Go
package webconnectivity
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import (
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"net"
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"net/url"
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"github.com/ooni/probe-cli/v3/internal/model"
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"github.com/ooni/probe-cli/v3/internal/netxlite"
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)
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// DNSAnalysisResult contains the results of analysing comparing
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// the measurement and the control DNS results.
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type DNSAnalysisResult struct {
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DNSConsistency *string `json:"dns_consistency"`
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}
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// DNSNameError is the error returned by the control on NXDOMAIN
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const DNSNameError = model.THDNSNameError
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var (
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// DNSConsistent indicates that the measurement and the
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// control have consistent DNS results.
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DNSConsistent = "consistent"
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// DNSInconsistent indicates that the measurement and the
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// control have inconsistent DNS results.
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DNSInconsistent = "inconsistent"
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)
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// DNSAnalysis compares the measurement and the control DNS results. This
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// implementation is a simplified version of the implementation of the same
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// check implemented in Measurement Kit v0.10.11.
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func DNSAnalysis(URL *url.URL, measurement DNSLookupResult,
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control ControlResponse) (out DNSAnalysisResult) {
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// 0. start assuming it's not consistent
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out.DNSConsistency = &DNSInconsistent
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// 1. flip to consistent if we're targeting an IP address because the
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// control will actually return dns_name_error in this case.
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if net.ParseIP(URL.Hostname()) != nil {
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out.DNSConsistency = &DNSConsistent
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return
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}
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// 2. flip to consistent if the failures are compatible
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if measurement.Failure != nil && control.DNS.Failure != nil {
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switch *control.DNS.Failure {
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case DNSNameError: // the control returns this on NXDOMAIN error
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switch *measurement.Failure {
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// When the Android getaddrinfo cache says "no data" (meaning basically
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// "I don't know, mate") _and_ the test helper says NXDOMAIN, we can
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// be ~confident that there's also NXDOMAIN on the Android side.
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//
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// See also https://github.com/ooni/probe/issues/2029.
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case netxlite.FailureDNSNXDOMAINError,
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netxlite.FailureAndroidDNSCacheNoData:
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out.DNSConsistency = &DNSConsistent
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}
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}
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return
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}
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// 3. flip to consistent if measurement and control returned IP addresses
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// that belong to the same Autonomous System(s).
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//
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// This specific check is present in MK's implementation.
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//
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// Note that this covers also the cases where the measurement contains only
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// bogons while the control does not contain bogons.
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//
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// Note that this also covers the cases where results are equal.
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const (
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inMeasurement = 1 << 0
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inControl = 1 << 1
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inBoth = inMeasurement | inControl
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)
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asnmap := make(map[int64]int)
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for _, asn := range measurement.Addrs {
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asnmap[asn] |= inMeasurement
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}
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for _, asn := range control.DNS.ASNs {
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asnmap[asn] |= inControl
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}
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for key, value := range asnmap {
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// zero means that ASN lookup failed
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if key != 0 && (value&inBoth) == inBoth {
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out.DNSConsistency = &DNSConsistent
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return
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}
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}
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// 4. when ASN lookup failed (unlikely), check whether
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// there is overlap in the returned IP addresses
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ipmap := make(map[string]int)
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for ip := range measurement.Addrs {
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ipmap[ip] |= inMeasurement
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}
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for _, ip := range control.DNS.Addrs {
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ipmap[ip] |= inControl
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}
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for key, value := range ipmap {
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// just in case an empty string slipped through
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if key != "" && (value&inBoth) == inBoth {
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out.DNSConsistency = &DNSConsistent
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return
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}
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}
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// 5. conclude that measurement and control are inconsistent
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return
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}
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